Walls

The Walls are the main setting where the Series takes place in. The Walls have existed since more than a century ago, when humanity was nearing extinction at the hands of the Titans, they made a group of three huge walls to protect their last stronghold. The walls reach about 50 metres in height. The tops of the walls are lined with cannons mounted on rails, which can fire on approaching Titans.

Because the walls are too long for humanity to guard their entire lengths, each Wall has four towns placed at points along their edges with another wall encircling it. Because Titans are drawn towards large concentrations of people, they focus their attacks on these towns, and humanity's defenses can be focused there.

A Titan within Wall Sina.

The interior of the walls seem to contain numerous dormant Titans. However no details have been given, it has been suggested that the walls were originally created by Titans using their hardening ability.

Two of the few people who know about the Titans in the walls are Pastor Nick and Historia Renz. Pastor Nick is a foremost member of a cult which considers the walls to be holy. Historia was a formerly high-born lady and presumably knows about the walls because of that.

Wall Maria is the outermost wall of the human kingdom, and thus the most expansive of their territory within. Because of its territory diameter, farmland and livestock, along with a massive forest of 80 meter tall trees were located here. Like the other walls, Wall Maria is approximately 50 meters in height. Five years ago, it was breached by the Colossal Titan after about 100 years of peace and prosperity, and about 20% of the population were killed, while the survivors retreated behind Wall Rose.

Wall Rose is the second outermost wall following Wall Maria. Its outer Trost Gate was breached by the Colossal Titan after 5 years of Wall Maria being breached, but has been covered by a boulder with the help of Eren Jaeger. It was thought to have been breached again after Titans appeared inside it.

Wall Sina is the innermost wall protecting the kingdom where the king and civilians related to him reside. The city inside Wall Sina is protected by the Military Police serving under the king, unlike the other branches of military, they don't use 3D Maneuver Gear on a daily basis except for certain occasions.